A. Field of the Invention
This invention relates generally to a method and apparatus for monitoring a receiver to determine the channel to which a receiver is tuned, and more particularly to a method and apparatus for determining the channel reception of a remotely controlled receiver.
B. Description of the Prior Art
Various arrangements have been employed to determine the channel to which a television receiver is tuned. A disadvantage of many known monitoring arrangements is that an internal connection to the television receiver is required. For example, Haselwood et al. U.S. Pat. No. 3,973,206, issued on Aug. 3, 1976 discloses a method of determining channel tuning by monitoring the varactor diode tuning voltage and thus, required internal connections in the television receiver.
Another method for determining channel tuning disclosed in Haselwood et al. U.S. Pat. No. 4,425,578, issued on Jan. 10, 1984 utilizes a signal injection source and a detector/receiver arranged to detect the combined signal from the injection signal source and a video carrier to which the video receiver is tuned. A significant drawback of signal injection monitoring arrangements is the potential interference with the functional operation of the video receiver being monitored.
U.S. patent application Ser. No. 893,183 to Fulmer et al., filed on Aug. 5, 1986, now U.S. Pat. No. 4,723,302 and assigned to the same assignee as the present application, discloses another method for determining channel tuning utilizing a local oscillator frequency measurement of the monitored receiver. The disclosed method and apparatus while effective for its intended purpose generally requires that a probe be positioned at a selected location in the monitored receiver and thus, requires physical access to the receiver.
Access to the tuning mechanism is becoming increasingly difficult with the advent of cable and pay television systems that utilize various converters and decoders, many of which are difficult to access.
Often a remote control system is used with the receiver enabling remote operation by a viewer for channel selection and turning the receiver ON and OFF. Additionally, remote control systems generally are available with cable tuners. Due to the increasing use of remote control systems with various receivers, such as broadcast radio receivers and video cassette recorders and cable converters used with a television receiver, at least one commercially available transmitter device, such as a General Electric device Model RRC600 Consumer Control Center, is used for remotely controlling multiple receivers. The RRC600 transmitter device learns and stores the infrared control signals used in various existing remote control systems of multiple devices so that this single transmitter is used instead of a separate transmitter for each remotely controlled device.